21600100 has 36 divisors (see below), whose sum is σ = 47654068. Its totient is φ = 8496000.

The previous prime is 21600091. The next prime is 21600121. The reversal of 21600100 is 100612.

It can be written as a sum of positive squares in 6 ways, for example, as 4691556 + 16908544 = 2166^2 + 4112^2 .

It is a Harshad number since it is a multiple of its sum of digits (10).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 4330 + ... + 7870.

Almost surely, 2^21600100 is an apocalyptic number.

21600100 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21600100, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23827034).

21600100 is an abundant number, since it is smaller than the sum of its proper divisors (26053968).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21600100 is a wasteful number, since it uses less digits than its factorization.

21600100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3616 (or 3609 counting only the distinct ones).

The product of its (nonzero) digits is 12, while the sum is 10.

The square root of 21600100 is about 4647.5907737235. The cubic root of 21600100 is about 278.4957597928.

Adding to 21600100 its reverse (100612), we get a palindrome (21700712).

The spelling of 21600100 in words is "twenty-one million, six hundred thousand, one hundred".